1. Field of the Invention
This invention relates to radiographic devices and is directed more particularly to an adapter assembly by which a radiographic cassette holder fitted to accommodate only large sized radiographic film cassettes is adapted to utilize a plurality of standard sizes of radiographic film.
2. Description of Prior Art
A radiographic film cassette is a portable light-proof container equipped with two fluorescing screens between which a radiographic film is enclosed. There are three basic film sizes used for conventional static radiography and each has its own standard cassette size, to wit: 14 .times. 17 inch film is enclosed in a standard 15 .times. 18 inch cassette; 10 .times. 12 inch film is enclosed in a standard 11 .times. 13 inch cassette; and 8 .times. 10 inch film is enclosed in a standard 9 .times. 11 inch cassette. Routine roentgenography utilizes upright holders and table trays which secure only the large cassettes, i.e. the 15 .times. 18 inch cassette when in a vertical position.
It is often appropriate to use a smaller film cassette, as for example in filming children or in obtaining small localized views of an area of particular concern to the radiologist. In such instances, it would be economical to use the intermediate sized film (10 .times. 12") or the small sized film (8 .times. 10"), the former representing a film cost savings of about 40% compared to the large sized film and the latter representing a film cost savings of about 60% compared to the large sized film. In addition, the area irradiated will usually be minimized with the use of the smaller films, which require coning of the X-ray beam. Resolution of the limited area of investigation will be correspondingly enhanced. Generally, such possible economical and radiobiological advantages are not realized by virture of the cassette holder accepting only the large (15 .times. 18") cassettes.